Compact eight-port MIMO/diversity antenna with band rejection characteristics

A new compact three-dimensional multiple-input-multiple-output (MIMO) antenna comprised of eight antenna elements is presented. The unit cell of the proposed MIMO/diversity antenna consists of three elliptical rings connected together in the region close to the feed line and a rectangular-shaped modified ground plane. To achieve polarization diversity with the proposed eight-port MIMO configuration, four antenna elements are horizontally arranged and the remaining four are vertically oriented. The proposed antenna has an impedance bandwidth (S-11 < -10 dB) of 25.68 GHz (3.1-28.78 GHz) with a wireless local area network notch-band at 5.8 GHz (5.2-6.5 GHz). In addition to polarization diversity, the proposed antenna provides a reliable link with wireless devices. The prototype antenna design is fabricated and measured for diversity performance. Also, the proposed MIMO antenna provides good performance metrics such as apparent diversity gain, channel capacity loss, envelope correlation coefficient, isolation, mean effective gain, multiplexing efficiency, and total active reflection coefficient.